|Twitter Header Dimensions 2015|
Twitter Header Dimensions / Sizes: 1500x500 pixels
Twitter Header Template 2015 - The New 2015 Twitter Header Dimensions
Profile Header Photo: Recommended dimensions are 1500x500 pixels.
Profile Photo: Recommended dimensions are 400x400 pixels.
While 1500x500 pixels is the recommended size, if you don't want Twitter to resize the image, you can get away with 1263x421 pixels.